Soft bounce
Definition
A soft bounce is a temporary email delivery failure, such as a full mailbox or an unavailable server, where the address may still be valid and deliverable later.
Why it matters
Soft bounces are counted rather than acted on individually. AeroCampaign escalates to a 90-day suppression after three soft bounces within a 30-day window, then lets the suppression expire so a recovered mailbox is not lost permanently.